Present day jet aircraft use a variety of propellents which have a varying density as they are compounded by the refineries. This, together with atmospheric temperature changes, can result in a wide density variation of fuel. It is desirable to provide a fuel volume gauging system in order that a reliable determination of actual weight of the fuel in the tank may be made. Two aspects are required; one, the liquid level, which provides a volumetric indication in the tank, and two, the density of the liquid which occupies that volume.
The prior art known to applicant consists of U.S. Pat. Nos. 1,526,850, 2,500,348, 2,620,661, 2,834,211, 3,154,946, 3,407,660, 3,437,771 and 3,572,122.